A known Ultra-High-Frequency (UHF) Satellite Communication (SATCOM) system consists of a constellation of approximately a half dozen satellites hovering over the equator. The downlink frequency of this system is between 243 MegaHertz (MHz) and 270 MHz. A subset of the UHF SATCOM system is the Fleet Broadcasting System whose one-way downlink operates in the 248 MHz to 255 MHz range. Radiations at these wavelengths are approximately 1 meter (m).
The antennas typically used for such wavelengths are quite large. The usual applicable shipboard antenna is in the form of a drum that is approximately 1.37 m in diameter. Another suitable shipboard antenna for such communication has crossed dipoles each of which has a length of approximately 0.5 m. The UHF SATCOM system and Fleet Broadcasting System are not known for sending messages directly to a person.
The hand-held satellite phones and global positioning systems (GPS) that are used directly by individuals are vulnerable to being easily jammed by strong signals radiated in the area of reception of the phone and GPS users. Patch antennas help mitigate these conditions. The high gain and narrow reception frequencies of the patch antenna can be used to advantage in such environments. Patch antenna gain of 6 to 8 dBi have been measured. Narrowband frequency applications of the patch antennas are made possible by the antenna's characteristic of resonating at wavelengths equal to twice the antenna's effective length
To provide a patch antenna for personal use, for example one being suitable for placement directly upon (worn by) a user, the physical size of the patch antenna must be considered. Several factors contribute to this size. The resonant frequency of the patch antenna conducting element is inversely related to the dielectric constant of the dielectric material used in the over-all patch antenna design. Increasing this dielectric constant increases the effective length of the antenna thereby enabling a physically smaller antenna than one having a lesser dielectric constant. The size of the ground plane also plays a role, though lesser, in patch antenna operating characteristics. A patch antenna, being a resonant element, compels a relatively narrow operating bandwidth.
There is a need for a relatively small and wearable narrowband antenna that is usable with satellite communication frequencies.